Selectivity and enormous H/D isotope effects on H atom abstraction by CH<sub>3</sub>radicals in solid methylsilane at 3.0 K–115 K
作者:Kenji Komaguchi、Yuko Ishiguri、Hiroto Tachikawa、Masaru Shiotani
DOI:10.1039/b206503g
日期:——
CH3SiH3 system, the CH3SiH2˙ radical was the major product immediately after the photolysis, while the ˙CH3 radical was the major one in the CH3SiD3 system. The ˙CH3 radicals decayed following first order kinetics in the dark in both systems. The decay rate constants for the reaction were experimentally determined to be k(Si–H) = 3.6 × 10−2 s−1 and k(Si–D) = 6.9 × 10−6 s−1 (k(Si–H)/k(Si–D) = 5.2 × 103) at
进行了一项 EPR 研究,以阐明甲基自由基 CH3SiH3 +˙CH3 → CH3SiH2˙ + CH4 在 3 K 的低温下,在含有 1 mol% CH3I 的 CH3SiH3 固溶体中从甲基硅烷 (CH3SiH3) 中夺取氢原子–115 K。在 77 K 的 CH3I 紫外光解后观察到的 EPR 光谱归因于 CH3SiH2˙ 自由基和˙CH3 自由基的混合物。在CH3SiH3体系中,CH3SiH2˙自由基是光解后的主要产物,而˙CH3自由基是CH3SiD3体系中的主要产物。在两个系统中,˙CH3 自由基在黑暗中按照一级动力学衰减。实验确定反应的衰减速率常数为 k(Si-H) = 3.6 × 10-2 s-1 和 k(Si-D) = 6.9 × 10-6 s-1 (k(Si-H) /k(Si-D) = 5.2 × 103) 在 77 K;